Many sports can be categorized by the intended use of one or both hands. Hand action in sports, however, cannot be discussed without describing the range of wrist joint motion, stability and flexibility to achieve the desired hand action. It will also be appreciated that two-handed sports, such as golf, baseball, hockey and others, have significantly different wrist and hand position requirements as compared with essentially one-handed sports, such as bowling and horseshoes, and the throwing sports, e.g., baseball and football. Proper hand/wrist action is a requirement in many different sports, whether they are one or two-handed hitting sports or one-handed tossing sports and is a function of the particular requirements for each sport.
The wrist joint, through tendon/muscle interactions in the forearm, allows the hand to move in five directions extension, flexion, abduction, adduction and circumduction. The vertical axis in two-handed hitting sports is referred to by a line formed through the thumb as it points upwardly. The horizontal axis is established 90.degree. to the vertical axis. The control of the speed of motion of the hand along the horizontal axis relative to the forearm is critical in sports that place a premium on directional control, e.g., golf, tennis, baseball batting (known collectively as hitting sports). Many factors are involved to properly strike the ball in each such sport. For example, the shape, speed, size and weight of the ball being struck, as well as the shape of the sport implement used to strike the ball, determine whether the stroke is successful. Upon analysis, however, hitting sports have two very common factors which determine the success or lack of success of properly striking the ball: the rate of speed of the ball at launch and its controlled placement upon launch, i.e., direction of launch. A powerful, well-timed stroke requires extreme athletic skill in hand/wrist action coordination. In hitting sports, such as baseball, where the ball is in motion when struck, hand/eye coordination is essential. Hand/eye coordination is not as essential in hitting sports where the ball is stationary when struck. In these latter sports, such as in golf, it is desirable to permit the angle of the striking implement surface relative to the horizontal plane to control the launch angle of the ball. Launch trajectory of the ball is controlled by the angle of approach of the hitting surface to the stationary ball. Ball rotation is critical in certain sports to control flight or path along surface, such as bowling. Such rotation may be achieved by rotation of the hand relative to the forearm. For example, polar rotation of the ball toward or away from the thrower occurs as a result of a palm-down or palm-up release position, respectively. A palm-to-the-side hand release position produces a hook or a slice. Thus, controlled wrist movement in extension, flexion, abduction, adduction and circumduction is essential in many sports to achieve desired ball control.
The wrist joint allows the hand to move relative to the forearm by the use of muscles and tendons in the forearm. Ligaments gives the wrist joint stability. The larger the joint area and the greater the range of motion of the extremities attached to the joint, the less effective is the stabilizing value of the ligaments, in contrast to the muscles and tendons. Thus, muscles and tendons become the key components, particularly in sports where substantial immobility of the wrist joint in certain directions is critical to properly strike an object ball. Various types of stabilizers and splints for the different joints of the human anatomy, particularly those used repetitively for sports activity, have been designed to stabilize such joints.
In the case of the wrist joint, the five involved motions in extension, flexion, abduction, adduction and circumduction are limited differently than in other joints. For example, left and right motion of the hand about a vertical axis from an anatomically neutral position is generally limited to about 45.degree., while abduction and adduction are limited to approximately 5.degree. and 15.degree., respectively. It will be appreciated that the anatomical neutral position of the hand relative to the forearm has 0.degree. flexion, adduction, abduction and circumduction, and 15.degree. extension. A sports-neutral position, however, for most hitting sports, requires an angle of 0.degree. in all movement directions. In certain sports, for example, golf, it is essential to maintain the sports-neutral position at least in flexion and extension before, on impact, and after impact with the ball. In anatomical terms, the radius and ulna should therefore lie in a plane generally parallel to a plane through the carpals or along the dorsal side of the hand. For a proper impact position in golf, that plane through the leading hand must also be parallel to the leading edge of the club. In two-handed hitting sports such as golf, the hand action or hand release is defined as a change (for a righthanded individual) of the left hand from pronation to supination and a change from supination to pronation by the trailing right hand. Thus, it is essential to maintain the sports-neutral position for the lead hand in flexion and extension, i.e., 0.degree., throughout the hitting motion. Absent substantial muscle and tendon development, which few obtain in their chosen sport, the necessary control of the hand and wrist action necessary to produce proper repetitive athletic skilled motion is elusive.